SaveHollywood is not ready to work on Snow Leopard. Apparently this extends to any software that runs older screen savers in the background -- they'll appear with a system message reading "not compatible."

If I open System Preferences' Screen Savers panel as usual, my system tells me that old screen savers are not compatible. But if I open System Preferences in 32-bit mode, they seem to work (in the panel, but not always when playing). So I tried the Terminal command from this older hint, but had the same problem. Finally I searched how to run a screen saver in 32-bit mode from Terminal. For that, you do this:

arch -i386 AppToRun

So to run an older screen saver in the background, you'd use this command:

I modified this hint to make 32-bit screen savers run as the normal system screen saver in 10.6. Now I can use Fenetres Volantes again!!
Basically, I wrote a script to check how long the computer had been idle, then run the screensaver terminal command, without the '-background' option, if the computer had been idle over a certain amount of time. Then I created a launchd plist to run the script every 90 seconds.

Here's how I did it:

1. Launch system preferences in 32-bit mode and assign a 32-bit screen saver
2. Make sure the delay to start the screen saver is set to "Never"
3. Make a file called scr32.sh and paste the following code in it. (Change the IDLE_WAIT_TIME variable from 900 to desired screen saver delay time)

/usr/bin/scr32.sh

#!/bin/sh

IDLE_WAIT_TIME=300 #Number of seconds to wait before starting screen saver

4. Save the file to the folder /usr/bin/
5. Make a file called com.GibsonTech.run32ScreenSaver.plist and paste the following code in it. (If you plan on having the screensaver start after less than 60 seconds of inactivity, you might want to change the StartInterval key here to something more appropriate for your needs)

That's about it. It currently only works for the active user. There are other places you can put the launchd plist to make it apply to all users, but if other users have a different screen saver configured this would probably screw it up.

this is too complicated. you can just change the unix executable in the screensaver.app.
rename the current one
cd /System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine
sudo mv ScreenSaverEngine ScreenSaverEngine-old
Then replace the old /System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine executable with an executable
#!/bin/sh
arch -i386 /System/Library/Frameworks/ScreenSaver.framework/Versions/A/Resources/ScreenSaverEngine.app/Contents/MacOS/ScreenSaverEngine32-old
Then you don't need any separate launch daemons or a separate mechanism to control the screensaver timer.